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OS/2 Shareware BBS: 10 Tools
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gbmsrc.zip
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gbmgif.c
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1999-01-17
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21KB
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897 lines
/*
gbmgif.c - Graphics Interchange Format support
Input options: index=# to get a given image in the file
Output options: xscreen=#,yscreen=#,background=#,xpos=#,ypos=#,transcol=#,ilace.
Fixed bugs in LZW compressor.
1. Don't need to write 'tail' at end, if no unprocessed input.
2. Writing 'tail' at end may increase code size.
*/
/*...sincludes:0:*/
#include <stdio.h>
#include <ctype.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <malloc.h>
#include "gbm.h"
#include "gbmhelp.h"
/*...vgbm\46\h:0:*/
/*...vgbmhelp\46\h:0:*/
/*...e*/
/*...suseful:0:*/
#define low_byte(w) ((byte) ( (w)&0x00ffU) )
#define high_byte(w) ((byte) (((unsigned)(w)&0xff00U)>>8))
#define make_word(a,b) (((word)a) + (((word)b) << 8))
/*...e*/
static GBMFT gif_gbmft =
{
"GIF",
"CompuServe Graphics Interchange Format",
"GIF",
GBM_FT_R1|GBM_FT_R4|GBM_FT_R8|
GBM_FT_W1|GBM_FT_W4|GBM_FT_W8,
};
#define GBM_ERR_GIF_BPP ((GBM_ERR) 1100)
#define GBM_ERR_GIF_TERM ((GBM_ERR) 1101)
#define GBM_ERR_GIF_CODE_SIZE ((GBM_ERR) 1102)
#define GBM_ERR_GIF_CORRUPT ((GBM_ERR) 1103)
#define GBM_ERR_GIF_HEADER ((GBM_ERR) 1104)
typedef struct
{
BOOLEAN ilace, errok;
int bpp;
byte pal[0x100*3];
} GIF_PRIV;
typedef unsigned int cword;
/*...sstep_ilace:0:*/
/* Pass 0 is all lines where y%8 == 0
Pass 1 is all lines where (y-4)%8 == 0
Pass 2 is all lines where (y-2)%4 == 0
Pass 3 is all lines where (y-1)%2 == 0
The complexity comes in when you realise there can be < 8 lines in total! */
static int step_ilace(int y, int h, int *pass)
{
switch ( *pass )
{
case 0: y += 8; break;
case 1: y += 8; break;
case 2: y += 4; break;
case 3: y += 2; break;
}
if ( y < h ) return y;
if ( *pass == 0 ) { *pass = 1; y = 4; if ( y < h ) return y; }
if ( *pass == 1 ) { *pass = 2; y = 2; if ( y < h ) return y; }
if ( *pass == 2 ) { *pass = 3; y = 1; }
return y;
}
/*...e*/
/*...sgif_qft:0:*/
GBM_ERR gif_qft(GBMFT *gbmft)
{
*gbmft = gif_gbmft;
return GBM_ERR_OK;
}
/*...e*/
/*...sgif_rhdr:0:*/
GBM_ERR gif_rhdr(const char *fn, int fd, GBM *gbm, const char *opt)
{
GIF_PRIV *gif_priv = (GIF_PRIV *) gbm->priv;
byte signiture[6], scn_desc[7], image_desc[10];
const char *index;
int img = -1, img_want = 0;
int bits_gct;
fn=fn; /* Suppress 'unref arg' compiler warnings */
/* Discover which image in GIF file we want */
if ( (index = gbm_find_word_prefix(opt, "index=")) != NULL )
sscanf(index + 6, "%u", &img_want);
gif_priv->errok = ( gbm_find_word(opt, "errok") != NULL );
/* Read and validate signiture block */
if ( gbm_file_read(fd, signiture, 6) != 6 )
return GBM_ERR_READ;
if ( memcmp(signiture, "GIF87a", 6) &&
memcmp(signiture, "GIF89a", 6) )
return GBM_ERR_BAD_MAGIC;
/* Read screen descriptor */
if ( gbm_file_read(fd, scn_desc, 7) != 7 )
return GBM_ERR_READ;
gif_priv->bpp = bits_gct = (scn_desc[4] & 7) + 1;
if ( scn_desc[4] & 0x80 )
/* Global colour table follows screen descriptor */
{
if ( gbm_file_read(fd, gif_priv->pal, 3 << bits_gct) != (3 << bits_gct) )
return GBM_ERR_READ;
}
else
/* Blank out palette, but make entry 1 white */
{
memset(gif_priv->pal, 0, 3 << bits_gct);
gif_priv->pal[3] =
gif_priv->pal[4] =
gif_priv->pal[5] = 0xff;
}
/* Expected image descriptors / extension blocks / terminator */
while ( img < img_want )
{
if ( gbm_file_read(fd, image_desc, 1) != 1 )
return GBM_ERR_READ;
switch ( image_desc[0] )
{
/*...s0x2c \45\ image descriptor:24:*/
case 0x2c:
if ( gbm_file_read(fd, image_desc + 1, 9) != 9 )
return GBM_ERR_READ;
gbm->w = make_word(image_desc[5], image_desc[6]);
gbm->h = make_word(image_desc[7], image_desc[8]);
gif_priv->ilace = ( (image_desc[9] & 0x40) != 0 );
if ( image_desc[9] & 0x80 )
/* Local colour table follows */
{
gif_priv->bpp = (image_desc[9] & 7) + 1;
if ( gbm_file_read(fd, gif_priv->pal, 3 << gif_priv->bpp) != (3 << gif_priv->bpp) )
return GBM_ERR_READ;
}
if ( ++img != img_want )
/* Skip the image data */
{
byte code_size, block_size;
if ( gbm_file_read(fd, &code_size, 1) != 1 )
return GBM_ERR_READ;
do
{
if ( gbm_file_read(fd, &block_size, 1) != 1 )
return GBM_ERR_READ;
gbm_file_lseek(fd, block_size, SEEK_CUR);
}
while ( block_size );
}
break;
/*...e*/
/*...s0x21 \45\ extension block:24:*/
/* Ignore all extension blocks */
case 0x21:
{
byte func_code, byte_count;
if ( gbm_file_read(fd, &func_code, 1) != 1 )
return GBM_ERR_READ;
do
{
if ( gbm_file_read(fd, &byte_count, 1) != 1 )
return GBM_ERR_READ;
gbm_file_lseek(fd, byte_count, SEEK_CUR);
}
while ( byte_count );
}
break;
/*...e*/
/*...s0x3b \45\ terminator:24:*/
/* Oi, we were hoping to get an image descriptor! */
case 0x3b:
return GBM_ERR_GIF_TERM;
/*...e*/
/*...sdefault:24:*/
default:
return GBM_ERR_GIF_HEADER;
/*...e*/
}
}
switch ( gif_priv->bpp )
{
case 1: gbm->bpp = 1; break;
case 2:
case 3:
case 4: gbm->bpp = 4; break;
case 5:
case 6:
case 7:
case 8: gbm->bpp = 8; break;
default: return GBM_ERR_GIF_BPP;
}
return GBM_ERR_OK;
}
/*...e*/
/*...sgif_rpal:0:*/
GBM_ERR gif_rpal(int fd, GBM *gbm, GBMRGB *gbmrgb)
{
GIF_PRIV *gif_priv = (GIF_PRIV *) gbm->priv;
byte *pal = gif_priv->pal;
int i;
fd=fd; /* Suppress 'unref arg' compiler warning */
memset(gbmrgb, 0x80, (sizeof(GBMRGB) << gbm->bpp));
for ( i = 0; i < (1 << gif_priv->bpp); i++ )
{
gbmrgb[i].r = *pal++;
gbmrgb[i].g = *pal++;
gbmrgb[i].b = *pal++;
}
return GBM_ERR_OK;
}
/*...e*/
/*...sgif_rdata:0:*/
/*...sread context:0:*/
typedef struct
{
int fd; /* File descriptor to read */
int inx, size; /* Index and size in bits */
byte buf[255+3]; /* Buffer holding bits */
int code_size; /* Number of bits to return at once */
cword read_mask; /* 2^code_size-1 */
} READ_CONTEXT;
static cword read_code(READ_CONTEXT *c)
{
dword raw_code; int byte_inx;
while ( c->inx + c->code_size > c->size )
/*...snot enough bits in buffer\44\ refill it:16:*/
/* Not very efficient, but infrequently called */
{
int bytes_to_lose = ((unsigned) c->inx >> 3);
byte bytes;
/* Note biggest code size is 12 bits */
/* And this can at worst span 3 bytes */
memcpy(c->buf, c->buf + bytes_to_lose, 3);
(c->inx) &= 7;
(c->size) -= (bytes_to_lose << 3);
if ( gbm_file_read(c->fd, &bytes, 1) != 1 )
return 0xffff;
if ( gbm_file_read(c->fd, c->buf + ((unsigned) c->size >> 3), bytes) != bytes )
return 0xffff;
(c->size) += (bytes << 3);
}
/*...e*/
byte_inx = ((unsigned) c->inx >> 3);
raw_code = c->buf[byte_inx] + ((c->buf[byte_inx + 1]) << 8);
if ( c->code_size > 8 )
raw_code += ((c->buf[byte_inx + 2]) << 16);
raw_code >>= ((c->inx) & 7U);
(c->inx) += (byte) (c->code_size);
return (cword) raw_code & c->read_mask;
}
/*...e*/
/*...soutput context:0:*/
typedef struct
{
int x, y, w, h, bpp, pass;
BOOLEAN ilace;
int stride;
byte *data, *data_this_line;
} OUTPUT_CONTEXT;
static void output(byte value, OUTPUT_CONTEXT *o)
{
if ( o->y >= o->h )
return;
switch ( o->bpp )
{
case 1:
if ( (o->x) & 7U )
o->data_this_line[(unsigned)(o->x) >> 3] |= (value << (7 - (((unsigned)o->x) & 7U)));
else
o->data_this_line[(unsigned)(o->x) >> 3] = (value << 7);
break;
case 4:
if ( (o->x) & 1U )
o->data_this_line[(unsigned)(o->x) >> 1] |= value;
else
o->data_this_line[(unsigned)(o->x) >> 1] = (value << 4);
break;
case 8:
o->data_this_line[o->x] = value;
break;
}
if ( ++(o->x) < o->w )
return;
o->x = 0;
if ( o->ilace )
{
o->y = step_ilace(o->y, o->h, &(o->pass));
o->data_this_line = o->data + (o->h - 1 - o->y) * o->stride;
}
else
{
(o->y)++;
o->data_this_line -= (o->stride);
}
}
/*...e*/
GBM_ERR gif_rdata(int fd, GBM *gbm, byte *data)
{
GIF_PRIV *gif_priv = (GIF_PRIV *) gbm->priv;
byte min_code_size; /* As read from the file */
int init_code_size; /* Initial code size */
cword max_code; /* 1 << code_size */
cword clear_code; /* Code to clear table */
cword eoi_code; /* End of information code */
cword first_free_code; /* First free code */
cword free_code; /* Next available free code slot */
word bit_mask; /* Output pixel mask */
int i, out_count = 0;
cword code, cur_code, old_code, in_code, fin_char;
cword *prefix, *suffix, *outcode;
READ_CONTEXT c;
OUTPUT_CONTEXT o;
BOOLEAN table_full = FALSE; /* To help implement deferred clear */
if ( (prefix = (cword *) malloc((size_t) (4096 * sizeof(cword)))) == NULL )
return GBM_ERR_MEM;
if ( (suffix = (cword *) malloc((size_t) (4096 * sizeof(cword)))) == NULL )
{
free(prefix);
return GBM_ERR_MEM;
}
if ( (outcode = (cword *) malloc((size_t) (4097 * sizeof(cword)))) == NULL )
{
free(suffix);
free(prefix);
return GBM_ERR_MEM;
}
if ( gbm_file_read(fd, &min_code_size, 1) != 1 )
{
free(outcode);
free(suffix);
free(prefix);
return GBM_ERR_READ;
}
if ( min_code_size < 2 || min_code_size > 9 )
{
free(outcode);
free(suffix);
free(prefix);
return GBM_ERR_GIF_CODE_SIZE;
}
/* Initial read context */
c.inx = 0;
c.size = 0;
c.fd = fd;
c.code_size = min_code_size + 1;
c.read_mask = (cword) (( 1 << c.code_size ) - 1);
/* Initialise pixel-output context */
o.x = 0;
o.y = 0;
o.pass = 0;
o.w = gbm->w;
o.h = gbm->h;
o.bpp = gbm->bpp;
o.ilace = gif_priv->ilace;
o.stride = ( (gbm->w * gbm->bpp + 31) / 32 ) * 4;
o.data = data;
o.data_this_line = data + (gbm->h - 1) * o.stride;
bit_mask = (word) ((1 << gif_priv->bpp) - 1);
/* 2^min_code size accounts for all colours in file */
clear_code = (cword) ( 1 << min_code_size );
eoi_code = (cword) (clear_code + 1);
free_code = first_free_code = (cword) (clear_code + 2);
/* 2^(min_code_size+1) includes clear and eoi code and space too */
init_code_size = c.code_size;
max_code = (cword) ( 1 << c.code_size );
while ( o.y < o.h && (code = read_code(&c)) != eoi_code && code != 0xffff )
{
if ( code == clear_code )
{
c.code_size = init_code_size;
max_code = (cword) ( 1 << c.code_size );
c.read_mask = (cword) (max_code - 1);
free_code = first_free_code;
cur_code = old_code = code = read_code(&c);
if ( code == 0xffff )
break;
fin_char = (cur_code & bit_mask);
output((byte) fin_char, &o);
table_full = FALSE;
}
else
{
cur_code = in_code = code;
if ( cur_code >= free_code )
{
cur_code = old_code;
outcode[out_count++] = fin_char;
}
while ( cur_code > bit_mask )
{
if ( out_count > 4096 )
{
free(outcode);
free(suffix);
free(prefix);
return gif_priv->errok ? GBM_ERR_OK : GBM_ERR_GIF_CORRUPT;
}
outcode[out_count++] = suffix[cur_code];
cur_code = prefix[cur_code];
}
fin_char = (cur_code & bit_mask);
outcode[out_count++] = fin_char;
for ( i = out_count - 1; i >= 0; i-- )
output((byte) outcode[i], &o);
out_count = 0;
/* Update dictionary */
if ( !table_full )
{
prefix[free_code] = old_code;
suffix[free_code] = fin_char;
/* Advance to next free slot */
if ( ++free_code >= max_code )
{
if ( c.code_size < 12 )
{
c.code_size++;
max_code <<= 1;
c.read_mask = (cword) (( 1 << c.code_size ) - 1);
}
else
table_full = TRUE;
}
}
old_code = in_code;
}
}
free(outcode);
free(suffix);
free(prefix);
if ( o.y < o.h && code == 0xffff )
/* If ran out of data and hadn't got to the end */
return gif_priv->errok ? GBM_ERR_OK : GBM_ERR_READ;
return GBM_ERR_OK;
}
/*...e*/
/*...sgif_w:0:*/
/*
We won't write any GIF89a or higher extensions into file.
Write palette as global colour table, not local.
*/
/*...swrite context:0:*/
typedef struct
{
int fd; /* Open file descriptor to write to */
int inx; /* Bit index into buf */
int code_size; /* Code size in bits */
byte buf[255+2]; /* Biggest block + overflow space */
} WRITE_CONTEXT;
static BOOLEAN write_code(cword code, WRITE_CONTEXT *w)
{
byte *buf = w->buf + ((unsigned)w->inx >> 3);
code <<= ((w->inx) & 7);
*buf++ |= (byte) code ;
*buf++ = (byte) (code >> 8);
*buf = (byte) (code >> 16);
(w->inx) += (w->code_size);
if ( w->inx >= 255 * 8 )
/* Flush out full buffer */
{
byte bytes = 255;
if ( gbm_file_write(w->fd, &bytes, 1) != 1 )
return FALSE;
if ( gbm_file_write(w->fd, w->buf, 255) != 255 )
return FALSE;
memcpy(w->buf, w->buf + 255, 2);
memset(w->buf + 2, 0, 255);
(w->inx) -= (255 * 8);
}
return TRUE;
}
static BOOLEAN flush_code(WRITE_CONTEXT *w)
{
byte bytes = ((unsigned)(w->inx + 7) >> 3);
if ( bytes )
{
if ( gbm_file_write(w->fd, &bytes, 1) != 1 )
return FALSE;
if ( gbm_file_write(w->fd, w->buf, bytes) != bytes )
return FALSE;
}
/* Data block terminator - a block of zero size */
bytes = 0;
return gbm_file_write(w->fd, &bytes, 1) == 1;
}
/*...e*/
typedef struct { cword tail; byte col; } DICT;
GBM_ERR gif_w(const char *fn, int fd, const GBM *gbm, const GBMRGB *gbmrgb, const byte *data, const char *opt)
{
int xpos = 0, ypos = 0;
int xscreen = gbm->w, yscreen = gbm->h;
int inx_background = 0, inx_transcol = -1;
BOOLEAN ilace;
/*...shandle options:8:*/
{
const char *s;
fn=fn; /* Suppress 'unref arg' compiler warnings */
if ( gbm->bpp != 1 && gbm->bpp != 4 && gbm->bpp != 8 )
return GBM_ERR_NOT_SUPP;
ilace = ( gbm_find_word(opt, "ilace") != NULL );
if ( (s = gbm_find_word_prefix(opt, "xscreen=")) != NULL )
sscanf(s + 8, "%d", &xscreen);
if ( (s = gbm_find_word_prefix(opt, "yscreen=")) != NULL )
sscanf(s + 8, "%d", &yscreen);
if ( (s = gbm_find_word_prefix(opt, "background=")) != NULL )
sscanf(s + 11, "%d", &inx_background);
if ( (s = gbm_find_word_prefix(opt, "xpos=")) != NULL )
sscanf(s + 5, "%d", &xpos);
if ( (s = gbm_find_word_prefix(opt, "ypos=")) != NULL )
sscanf(s + 5, "%d", &ypos);
if ( (s = gbm_find_word_prefix(opt, "transcol=")) != NULL )
{
if ( gbm_same(s+9, "edge", 4) )
switch ( gbm->bpp )
{
case 8: inx_transcol = *data; break;
case 4: inx_transcol = *data >> 4; break;
case 1: inx_transcol = *data >> 7; break;
}
else
sscanf(s + 9, "%d", &inx_transcol);
}
}
/*...e*/
/*...swrite header etc\46\:8:*/
{
byte scn_desc[7], image_desc[10]; int p;
char *sig = ( inx_transcol != -1 ) ? "GIF89a" : "GIF87a";
/* Write signiture */
if ( gbm_file_write(fd, sig, 6) != 6 )
return GBM_ERR_WRITE;
/* Write screen descriptor */
scn_desc[0] = low_byte(xscreen);
scn_desc[1] = high_byte(xscreen);
scn_desc[2] = low_byte(yscreen);
scn_desc[3] = high_byte(yscreen);
scn_desc[4] = (0x80 | ((gbm->bpp - 1) * 0x11));
/* Global colour table follows */
/* Quality bpp == gct bpp == gbm->bpp */
scn_desc[5] = (byte) inx_background;
scn_desc[6] = 0;
if ( gbm_file_write(fd, scn_desc, 7) != 7 )
return GBM_ERR_WRITE;
/* Write global colour table */
for ( p = 0; p < (1 << gbm->bpp); p++ )
{
byte pal[3];
pal[0] = gbmrgb[p].r;
pal[1] = gbmrgb[p].g;
pal[2] = gbmrgb[p].b;
if ( gbm_file_write(fd, pal, 3) != 3 )
return GBM_ERR_WRITE;
}
if ( inx_transcol != -1 )
/* Do GIF89a "Graphic Control Extension" application extension block */
{
char gce[8];
gce[0] = 0x21; /* Extension Introducer */
gce[1] = (char) 0xf9; /* Graphic Control Label */
gce[2] = 4; /* Block size */
gce[3] = 0x01; /* No 'disposal', no 'user input' */
/* Just transparent index present */
gce[4] = 0; /* Delay time, 0 => not set */
gce[5] = 0; /* Delay time, 0 => not set */
gce[6] = (char) inx_transcol; /* Transparent colour index */
gce[7] = 0; /* Block size, 0 => end of extension */
if ( gbm_file_write(fd, gce, 8) != 8 )
return GBM_ERR_WRITE;
}
/* Do image descriptor block */
image_desc[0] = (byte) 0x2c;
image_desc[1] = low_byte(xpos);
image_desc[2] = high_byte(xpos);
image_desc[3] = low_byte(ypos);
image_desc[4] = high_byte(ypos);
image_desc[5] = low_byte(gbm->w);
image_desc[6] = high_byte(gbm->w);
image_desc[7] = low_byte(gbm->h);
image_desc[8] = high_byte(gbm->h);
image_desc[9] = gbm->bpp - 1;
/* Non-interlaced, no local colour map, no sorted palette */
if ( ilace )
image_desc[9] |= 0x40; /* Interlaced */
if ( gbm_file_write(fd, image_desc, 10) != 10 )
return GBM_ERR_WRITE;
}
/*...e*/
/*...sLZW encode data\44\ tail\43\col lookup version:8:*/
/*
hashvalue is calculated from a string of pixels cumulatively.
hashtable is searched starting at index hashvalue for to find the entry.
hashtable is big enough so that MAX_HASH > 4*MAX_DICT.
*/
#define MAX_HASH 17777 /* Probably prime and > 4096 */
#define MAX_DICT 4096 /* Dictionary size */
#define INIT_HASH(p) (((p)+3)*301) /* Initial hash value */
{
int stride = ((gbm->w * gbm->bpp + 31) / 32) * 4;
byte min_code_size;
int init_code_size, x, y, pass;
cword clear_code, eoi_code, last_code, max_code, tail;
unsigned int hashvalue, lenstring, j;
DICT *dict, **hashtable;
WRITE_CONTEXT w;
/* Now LZW encode data */
if ( (dict = (DICT *) malloc((size_t) (MAX_DICT * sizeof(DICT)))) == NULL )
return GBM_ERR_MEM;
if ( (hashtable = (DICT **) malloc((size_t) (MAX_HASH * sizeof(DICT *)))) == NULL )
{
free(dict);
return GBM_ERR_MEM;
}
/* Initialise encoder variables */
init_code_size = gbm->bpp + 1;
if ( init_code_size == 2 )
/* Room for col0, col1, cc, eoi, but no others! */
init_code_size++;
min_code_size = init_code_size - 1;
if ( gbm_file_write(fd, &min_code_size, 1) != 1 )
{
free(hashtable);
free(dict);
return GBM_ERR_WRITE;
}
clear_code = ( 1 << min_code_size );
eoi_code = clear_code + 1;
last_code = eoi_code;
max_code = ( 1 << init_code_size );
lenstring = 0;
/* Setup write context */
w.fd = fd;
w.inx = 0;
w.code_size = init_code_size;
memset(w.buf, 0, sizeof(w.buf));
if ( !write_code(clear_code, &w) )
{
free(hashtable);
free(dict);
return GBM_ERR_WRITE;
}
for ( j = 0; j < MAX_HASH; j++ )
hashtable[j] = NULL;
data += ( (gbm->h - 1) * stride );
for ( y = pass = 0; y < gbm->h; )
{
const byte *pdata = data - y * stride;
for ( x = 0; x < gbm->w; x++ )
{
byte col;
/*...sget col:24:*/
switch ( gbm->bpp )
{
case 8:
col = *pdata++;
break;
case 4:
if ( x & 1 )
col = (*pdata++ & 0x0f);
else
col = (*pdata >> 4);
break;
default: /* must be 1 */
if ( (x & 7) == 7 )
col = (*pdata++ & 0x01);
else
col = ((*pdata >> (7-(x&7))) & 0x01);
break;
}
/*...e*/
/*...sLZW encode:24:*/
if ( ++lenstring == 1 )
{
tail = col;
hashvalue = INIT_HASH(col);
}
else
{
hashvalue *= ( col + lenstring + 4 );
j = ( hashvalue %= MAX_HASH );
while ( hashtable[j] != NULL &&
( hashtable[j]->tail != tail ||
hashtable[j]->col != col ) )
if ( ++j >= MAX_HASH )
j = 0;
if ( hashtable[j] != NULL )
/* Found in the strings table */
tail = (hashtable[j]-dict);
else
/* Not found */
{
if ( !write_code(tail, &w) )
{
free(hashtable);
free(dict);
return GBM_ERR_WRITE;
}
hashtable[j] = dict + ++last_code;
hashtable[j]->tail = tail;
hashtable[j]->col = col;
tail = col;
hashvalue = INIT_HASH(col);
lenstring = 1;
if ( last_code >= max_code )
/* Next code will be written longer */
{
max_code <<= 1;
w.code_size++;
}
else if ( last_code >= MAX_DICT-2 )
/* Reset tables */
{
if ( !write_code(tail , &w) ||
!write_code(clear_code, &w) )
{
free(hashtable);
free(dict);
return GBM_ERR_WRITE;
}
lenstring = 0;
last_code = eoi_code;
w.code_size = init_code_size;
max_code = ( 1 << init_code_size );
for ( j = 0; j < MAX_HASH; j++ )
hashtable[j] = NULL;
}
}
}
/*...e*/
}
if ( ilace )
y = step_ilace(y, gbm->h, &pass);
else
y++;
}
free(hashtable);
free(dict);
if ( lenstring != 0 )
{
if ( !write_code(tail, &w) )
return GBM_ERR_WRITE;
if ( ++last_code >= max_code )
/* Next code will be written longer */
w.code_size++;
}
if ( !write_code(eoi_code, &w) ||
!flush_code( &w) )
return GBM_ERR_WRITE;
}
/*...e*/
/*...swrite terminator:8:*/
{
byte term = (byte) 0x3b;
if ( gbm_file_write(fd, &term, 1) != 1 )
return GBM_ERR_WRITE;
}
/*...e*/
return GBM_ERR_OK;
}
/*...e*/
/*...sgif_err:0:*/
const char *gif_err(GBM_ERR rc)
{
switch ( (int) rc )
{
case GBM_ERR_GIF_BPP:
return "bad bits per pixel";
case GBM_ERR_GIF_TERM:
return "terminator found before requested image descriptor";
case GBM_ERR_GIF_CODE_SIZE:
return "code size not in range 2 to 9";
case GBM_ERR_GIF_CORRUPT:
return "encoded data is corrupt";
case GBM_ERR_GIF_HEADER:
return "bad header";
}
return NULL;
}
/*...e*/